This research proposal is designed to examine the slime glycolipoprotein (GLP) of Pseudomonas aeruginosa in its antigenic capacity to stimulate the production of protective antibodies. The nature of the protective activity in mice of anti-GLP serum will be elucidated by in vivo and in vitro experiments. The interactions among anti-GLP serum or the IgM and IgG immunoglobulin fractions, heat-labile serum factors (essentially complement), polymorphonuclear leukocytes, and macrophages will be studied in the phagocytosis and killing of P. aeruginosa. The factors that influence the slime-GLP inhibition of phagocytosis, in the absence of antiserum, will be determined. The nature and specificity of the interaction between slime GLP, leukocytes, and leukocyte-plasma membranes will be examined. The possible interaction of slime GLP with complement also will be assessed. Complementing the ongoing slime-GLP fragmentation studies, wild-type slime GLP, mutant-slime GLP, and slime GLP-changes induced through phage lysogenization will be examined in regard to chemical and biologic properties (leukopenia, lethality, inhibition of phagocytosis, antigenic specificity, and ability to stimulate production of antibodies). The effect of these changes in slime GLP and killing by leukocytes will also be determined. Fragments derived from the slime-GLP molecule suggest that leukopenia and lethality are associated with the lipid, while the inhibition of phagocytosis and antigenic specificity is a function of the polysaccharide. Antibodies produced against these components of the slime GLP will be assessed in protection against leukopenia and lethality in vivo, and in phagocytosis and killing by leukocytes in vitro.